The present invention relates to an intermediate disconnecting tool intended to be placed in a lower assembly lowered into a fluid exploitation well, of the type comprising:                an upper portion, intended to be connected to a cable working line, and a lower portion, intended to be connected to a bottom tool, the upper portion and the lower portion being mounted so as to move relative to each other between a position connected on each other and a completely disconnected position, in which the upper portion can be raised to the surface independently of the lower portion, one of the upper portion and of the lower portion defining a head, the other of the upper portion and the lower portion defining a receiving cavity receiving the head sealably in the connected position;        at least one immobilization member that can be freed from the upper portion relative to the lower portion in the connected position;        a member for releasing the immobilization member, mounted able to move between an activation position for activating the immobilization member and a release position for releasing the immobilization member;        a mechanism for moving the release member housed in the tool, the movement mechanism comprising an actuator including an energy source, and a receptor receiving a control signal capable of powering the actuator via the energy source when the control signal is received.        
To perform operations and/or measurements in a fluid exploitation well, it is known to lower intervention and/or measuring tools by positioning them in a lower assembly placed at the lower end of a cable working line. The lower assembly is lowered into the well using the cable working line to the operating and/or measuring point.
The cable working line is for example a smooth cable (referred to as a “slickline”), a stranded cable of the electric line type, or a coiled hollow flexible tube of the “coiled tubing” type.
Lowering the tool using such a line is easier to do than with drill rods, in particular when the line is a slickline.
However, once introduced into the well, under certain circumstances, the lower assembly remains blocked at the bottom of the well. This blocking can come, for example, from poor alignment of the lower assembly, an overly small local incline of the well, or poor operation of an anchoring or sealing system of the lower assembly.
In that case, the surface operator tries, for example, to exert a significant tractive force on the lower assembly using the cable working line to try to unblock the lower assembly. However, this maneuver is risky, since it can lead to breaking the cable working line. Subsequent fishing for the lower assembly remaining at the bottom of the well is then very complicated and the cable working line must be replaced, which can be expensive.
In certain cases, the lower assembly is provided with a slide making it possible to perform jarring to try to unjam the lower assembly. However, the impacts caused by the jarring can damage certain tools, in particular certain measuring tools including sensors sensitive to impacts.
To offset all of these problems, intermediate disconnecting tools have been designed to perform a controlled disconnection of the lower assembly relative to the cable working line. These tools make it possible to raise the cable working line independently of the lower assembly and subsequently lower a retrieval tool better suited to unjamming the part of the lower assembly remaining at the bottom.
To that end, known for example is a disconnecting tool that is activated mechanically by making an object fall sliding along the cable working line to a release member of the line situated at the upper end of the lower assembly. Such a device is not fully satisfactory, in particular in inclined wells.
Also known from U.S. Pat. No. 5,984,006 is an intermediate disconnecting tool comprising an explosive load that can be triggered by a control signal transmitted from the surface via the stranded electrical cable. The explosive load installed in a tool of the lower assembly provides the necessary energy to a piston actuator that moves in the tool to release the cable working line. Other systems without explosive loads exist, but with the necessary energy transported from the surface via the electrical cable.
Such a tool is not completely satisfactory. It is in fact necessary to convey sufficient electrical power to the lower assembly to actuate the system or cause the explosion of the load that will actuate the system, which is in particular not possible when a slickline is used. Moreover, the explosive load necessary to move the piston can damage the tool.
One aim of the invention is therefore to obtain a disconnecting tool for a lower assembly jammed in the bottom of a well that is simple to actuate from the surface without a risk of damaging the tool.
To that end, the invention relates to a disconnecting tool of the aforementioned type, characterized in that the movement mechanism comprises at least one member for elastic stressing of the release member towards its release position and at least one retaining member for keeping the release member in its activation position against the stressing member, the actuator being able to release the retaining member after receiving the control signal.